1. Field of the Invention
This invention generally relates to laser scanning systems for, and methods of, scanning, reading and/or analyzing bar code symbols. More particularly, this invention relates to a laser scanning workstation which is self-supporting on a support surface and which is portable from place to place due to its light-weight and small size and low volume characteristics. Still more particularly, this invention relates to a laser-based data acquisition terminal and to a novel method of reading bar code symbols.
2. Description of the Prior Art
Various laser scanning systems have been developed for many processing industries to read bar code symbols, which uniquely identify an object to be processed, to decode the symbol to a multiple digit representation for recordkeeping and inventory control purposes.
For example, blood-banks have begun to identify blood bags with bar code symbols to facilitate processing. The need has arisen to quickly and accurately scan coded blood bags.
Furthermore, the magazine distribution industry widely distributes magazines on a consignment basis, and therefore the need exists for accurately and quickly tallying the returned magazines for credit validation. Similarly, the record and tape industry requires accurate inventory information of its sold and returned products.
There are several laser scanning systems in current use. For example, there are point-of-sale or deck scanners which are large, massive and stationary installations which are built into an immovable structure such as a supermarket counter. In these scanners, the symbol must be oriented face-down during passage of the object through the system. Hence, it is difficult to register the symbol with the laser light beam emitted from the system.
Other systems include contact-type and non-contact-type wand or pen bar code readers which are positioned on or near the symbol, and then manually dragged across the symbol. However, criticality is required to manipulate the angle of the pen relative to the symbol, the pen speed, the pen pressure and the uniformity of pen speed. The pen readers are time-and labor-consuming.
Still other laser scanning systems have recently been designed which can be hand-held. However, the known hand-held laser scanning heads, although very light-in-weight, are not altogether convenient to use in assembly-line applications where the handler is processing coded objects all day long. In some applications, the hand-held heads are somewhat difficult to manipulate easily. In all cases, the hand-held laser scanning heads are required to be held by the handler, thereby restricting one of his hands from assisting directly in the manual processing of the objects to be scanned.